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Long-term stability of international reference preparations for thromboplastins
A M van den Besselaar1, J Hermans, H Beeser
1Department of Haematology, University Hospital, Leiden, The Netherlands.
Insights
Certified reference thromboplastins show no signs of deterioration over time. Long-term stability monitoring by multiple labs is recommended to account for laboratory-specific variations.
Area of Science:
- Clinical Chemistry
- Biotechnology
- Medical Diagnostics
Background:
- Certified reference materials (CRMs) are crucial for standardizing thromboplastin reagents.
- Accurate calibration of thromboplastins is essential for effective oral anticoagulant therapy monitoring.
- The Community Bureau of Reference (BCR) provides CRMs for thromboplastin calibration.
Purpose of the Study:
- To assess the long-term stability of BCR-certified reference thromboplastins.
- To evaluate potential trends in prothrombin time (PT) and PT ratios over time.
- To determine if reference materials exhibit deterioration.
Main Methods:
- Monitoring of deep-frozen and lyophilized plasma samples over a five-year period (1981-1986).
- Measurement of prothrombin times and prothrombin time ratios on 19 separate occasions.
- Statistical analysis for time-dependent trends in PT and PT ratios.
Main Results:
- Significant trends in prothrombin time and prothrombin time ratio were observed (P < 0.05).
- No consistent pattern of trends across laboratories was identified.
- Observed trends are likely attributable to variations in local laboratory conditions, not material degradation.
Conclusions:
- The BCR-certified reference thromboplastins demonstrate stability and have not deteriorated.
- Variations in laboratory conditions can influence prothrombin time measurements.
- Simultaneous monitoring by at least two independent laboratories is recommended for robust stability assessment.
Abstract:
Three certified reference materials for thromboplastins are available from the Community Bureau of Reference (BCR) of the European Commission for calibration of commercial thromboplastins used for control of oral anticoagulant therapy. The long-term stability of these reference materials has been monitored by two independent laboratories, using deep-frozen and lyophilized plasma samples. Prothrombin times and prothrombin time ratios measured on 19 occasions in the period 1981-86 have been analysed for trend with time. Although significant trends of prothrombin time and ratio (P less than 0.05) were observed, a consistent pattern of trends could not be recognized. The significant trends of prothrombin time and prothrombin time ratio are most probably due to changes in local laboratory conditions. There is no indication that the reference materials have deteriorated since the beginning of the study. It is recommended that long-term stability monitoring of thromboplastins be performed by at least two laboratories simultaneously.
